This invention relates generally to neutralization of explosive devices, such as land mines, underwater mines, unexploded ordnance (UXO), bombs, etc. More particularly, the present invention relates to a system for neutralizing an explosive device with substantially no collateral damage.
Various explosive devices have been and may continue to be deployed around the world. These explosive devices are present in various forms and provide various threats to people, vehicles, livestock, and other property that may be near such explosive devices. For example, explosive devices may include anti-personnel or anti-vehicle land mines, or underwater mines which are targeted to destroy or damage surface or submarine vessels. In addition, unexploded ordinance (UXO) may be located near, and present a threat to, people and property. Examples of UXO include various ammunition such as aerial bombs, or shells, which may be armed but have not yet exploded. Unknown or unforeseen conditions may cause the UXO to explode inadvertently with potentially disastrous results.
In addition, various types of explosive devices, sometimes termed bombs, can be assembled and deployed in areas where an explosion could threaten people or property. For example, such a bomb may be formed and positioned by an individual in a public area of a city. Often the triggering parameters of such a bomb are either unknown and/or out of the control of authorities who would otherwise desire to disable the bomb. For each of the above-described explosive devices, it is desirable to disable the system to avoid inadvertent damage to nearby people and property.
One traditional method of disabling explosive devices is to disarm them. Disarming can entail the disconnecting of the detonator or triggering mechanism from the explosive charge. Unfortunately, the appropriate manner of such disconnection may be difficult to determine or difficult to implement, or both, resulting in a highly dangerous situation for the person disarming the explosive. Further, even after being successfully disarmed, the explosive charge may still pose a danger of explosion due to other known or unknown mechanisms. Therefore, the explosive charge must still be neutralized or otherwise disposed of.
Another traditional method of disabling an explosive device is removing and transporting the system to a location that poses less danger to people and property, and detonating the explosive device there. Unfortunately, the removal of the explosive device without detonation may prove to be impossible, impractical, or difficult. For example, during a removal attempt there may be an inadvertent explosion and damage to people and/or property. Further, even if the explosive device was successfully removed, an inadvertent explosion and/or damage may occur during transit of the explosive device to a desired detonation location. Finally, even if the explosive system is successfully removed and transported to a desired detonation location, the detonation will necessarily involve collateral damage at the detonation site or require the provision of an explosion-resistant container.
The explosive device can also be conventionally disabled by in-place detonation where the explosive charge is triggered to explode. This method is often practiced in the case of land mines. FIG. 1 depicts one example of a land mine 10 that is buried in the ground 12 below the ground surface 14. While the land mine 10 shown in FIG. 1 is covered with soil, such mines can also be covered with foliage or other camouflage, or can be uncovered. Mines of this type can be mechanically or non-mechanically (e.g., influence-type) activated. An influence-type mine contains an explosive bulk charge which is triggered by nonmechanical external conditions. For example, such a mine can be triggered by the detection of a sufficiently large and sufficiently close metal object. In contrast, a mechanically activated land mine is triggered in response to mechanical application of a force to one or more parts of the land mine. For example, in the land mine 10 shown in FIG. 1, a triggering device 16 is connected to a bulk charge 18 that is explosive. The triggering device 16 can include one or more plates supported by one or more springs. When a sufficient amount of pressure is imparted to the plates of the triggering device 16, for example due to a person or vehicle moving onto the portion of the ground surface 14 directly above the triggering device 16, the plates can press down. Under certain predetermined conditions of pressure or time, a fuse within the triggering device 16 can be initiated, which in turn detonates the bulk charge 18. The bulk charge can be formed of various materials such as trinitrotoulene (TNT), Composition-B, or some other explosive material.
With such an explosive device, an example of in-place detonation is shown in FIG. 1. An explosive charge 20 can be disposed on or near the ground surface 14. The explosive charge 20 can be a conventional explosive that can be remotely detonated through known methods. Such conventional explosives can include TNT, Composition-B, or others such as dilute explosive tile (DET) available from SRI International of Menlo Park, California. As the explosive charge 20 explodes, material and energy travel away from the explosive charge 20. As the material and energy from the explosive charge 20 travel in the direction of and to the land mine 10, the land mine 10, and more particularly the bulk charge 18, may experience a particular peak pressure for a particular duration, both of which are sufficient to trigger and therefore explode the bulk charge 18.
Unfortunately, the effectiveness of an explosive charge 20 formed of conventional explosives is strongly effected by how much material is between the explosive charge 20 and the land mine 10. When underground, this amount can be characterized by the medium depth MD of the medium (here the ground or soil) between the explosive charge 20 and the land mine 10 through which the explosive material and energy travels. The effectiveness is also strongly affected by the type of the ground 12 or other intervening medium between the explosive charge 20 and the land mine 10. Also, the effectiveness is affected by the overall distance from the land mine 10 to the explosive charge 20. For example, this distance is greater when there is more lateral offset between the explosive charge 20 and the land mine 10, and increases when the explosive charge 20 is exploded at larger heights above the ground surface 14.
Due to each of the foregoing factors, conventional explosive charges 20 can be unreliable for neutralizing underground land mines with a medium depth MD of greater than 10 centimeters. Also, because the land mine may be detonated by the reaction of the bulk charge 18 itself, and not the triggering device 16, the effectiveness of the conventional explosive charge 20 is affected by the particular type of bulk charge 18 used in the land mine 10. More specifically, the effectiveness is influenced by the required peak pressure and or duration required for detonating the type of material that forms the bulk charge 18.
Instead of a conventional explosive, a shaped explosive charge 22 can be used for in-place detonation of the land mine 10, as shown in FIG. 2. As shown in FIG. 1, the conventional explosive charge 20 essentially explodes with material and energy directed substantially equally in all directions. In contrast, the shaped explosive charge 22 can be configured such that when exploded, the material and energy (sometimes referred to as the "jet" and including hot molten material such as copper) are projected outward in one or more predetermined directions, with reduced or substantially no projection in other directions. Thus, the shaped explosive charge 22 can be placed near or on the land mine 10, for example near or on the ground surface 14, and remotely detonated. Upon such explosion, the jet can project into the land mine 10 with sufficient pressure and/or duration to detonate the bulk charge 18.
Unfortunately, like the conventional charge 20 of FIG. 1, the shaped explosive charge 22 effectiveness is strongly affected by the overall distance between the shaped explosive charge 22 and the land mine 10, the medium depth MD under which the land mine is disposed, and the type of ground 12 or other medium that is disposed between the shaped explosive charge 22 and the land mine 10. Also, like the conventional explosive charge 20 of FIG. 1, because the bulk charge 18 is exploded without operation of the triggering device 16, the effectiveness of the shaped explosive charge 22 in imparting the appropriate peak pressure and/or duration of such peak pressure is effected by the type of bulk charge 18 used in the land mine 10. As a further disadvantage, because a significant amount of the energy from the explosion of the shaped explosive charge 22 is directed substantially in a single particular direction, the jet can be strongly affected by obstacles in the medium between the shaped explosive charge 22 and the land mine 10. In particular, the jet can be deflected if the leading point of the jet encounters such an obstacle. Further, because the energy of the exploded shaped explosive 22 is directed and concentrated in a particular direction, the jet can puncture the land mine 10 without actually exploding the bulk charge 18. Thus, if the triggering device 16 is still operative after the shaped explosive charge 22 is exploded, the land mine 10 will remain active and may inadvertently explode under certain conditions.
Another prior art method of in-place detonation involves explosively formed penetrators (EFP), or self-forging fragments. A detonating device can be disposed some distance away from the targetted land mine, for example above the ground surface, and exploded. Upon such explosion, fragments and penetrators are formed and projected toward the explosive device. When the fragments and penetrators penetrate into the device bulk charge, they can produce the required peak pressure for the required duration to produce detonation of the bulk charge. Unfortunately, the effectiveness of the EFPs are strongly effected by the overall distance between the EFP device and the land mine, the amount and type of intervening material, and the type of explosive used for the bulk charge.
Therefore, it is desired to have an apparatus and method for neutralizing explosive devices that are more effective, are less sensitive to the medium depth MD, less sensitive to intervening obstacles, and less sensitive to the type of explosive material used for the bulk charge. Further, it is desired that such an apparatus and method disable the explosive device without exploding the bulk charge, thereby substantially avoiding collateral damage.